Mobile phones require a small antenna for signal transmission and reception. Microstrip antennas, including planar inverted-F antennas (PIFAs), are, in general, suitable for that purpose. One of the known features of microstrip antennas is a narrow bandwidth they possess. Several different techniques for widening the bandwidth of PIFAs have been used or proposed. For example, the bandwidth of a PIFA can be altered by changing the size and the shape of the patch. Bandwidth widening can also be achieved by using parasitic patches disposed adjacent to the radiator. Different materials such as dielectrics of photonic bandgap structures (PBGs) have been used to load the radiator. In most cases, implementing the bandwidth widening feature increases the cost of antennas significantly or the volume of the antenna radiator.
It is advantageous and desirable to provide a method and device for efficiently widening the bandwidth of a PIFA in a hand-held electronic device without the disadvantages of the prior art techniques.